IP Case Law Analysis

Caution Needed When Using Terms of Art in Patent Claims

August 1, 2012

What This Means To You

Use a term of art in a patent either as one of ordinary skill in the art would use it or with a broad definition of the term by non-limiting example.

To expand the meaning of a term beyond what is disclosed in the specification, carefully consider whether to offer a claim differentiation theory, by which the presence of a limitation in a dependent claim gives rise to a rebuttable presumption that the limitation is not present in a parent claim.

Tailor claim construction arguments based on the composition of the Federal Circuit panel construing the claim.

The Federal Circuit determined that the district court’s claim construction accorded too much weight to extrinsic evidence, such as expert testimony, but did not decide whether the scope of the disputed term was limited to or expanded beyond the embodiment described in the specification.

Case Background

InterDigital sued Nokia for allegedly violating the Tariff Act by importing mobile phone handsets that infringed InterDigital’s patent, which related to initiating communication between a mobile phone and a base station. The patent described only one type of “code” – a conventional “spreading code” – but described the spreading code being used in an unconventional way. The independent claims recited a “code,” and a dependent claim limited the “code” to be a “spreading code.”

Since the specification described only spreading codes, the district court construed the term “code,” as recited in the independent claim, to mean “spreading code.” Based on expert testimony regarding the meaning of the phrase “spreading code” to one of ordinary skill in the art, the district court construed the phrase “spreading code” to cover spreading codes used in conventional ways, but not spreading codes used in the unconventional way described in the specification. Using this claim construction, the district court held that Nokia did not infringe InterDigital’s patent.

Decision Analysis

In vacating the district court’s claim construction and finding of non-infringement, a divided Federal Circuit panel reached no decision as to the proper construction of the term “code.” The panel majority stated that the term could be construed to mean spreading codes and other codes, noting that the use of claim differentiation gave rise to a presumption that the term “code” as used in the independent claim was broader than the phrase “spreading code” as used in the dependent claim.

The Court then went on to state that the term “code” could also be construed to mean only the spreading codes described in the specification, noting that the presumption arising from claim differentiation might impermissibly extend the scope of the term “code” beyond the embodiments described in the specification.

In dissent, Judge Newman adopted the district court’s claim construction.

Takeaways

For patent applicants, we recommend either using a term of art as one of ordinary skill in the art would use it, or providing a broad, clear definition of the term by non-limiting example. Implicitly extending the scope of a term of art to cover an inventive concept creates ambiguities that may not be construed in the applicant’s favor.

For accused infringers, we recommend tailoring claim construction arguments based on the composition of the Federal Circuit panel that is construing the claim. For example, Judge Newman’s deference to the district court’s factual findings in this case is consistent with her dissents in Phillips v. AWH Corporation. Likewise, the tension between the dueling claim constructions offered by the panel majority is consistent with the tension between Judge Bryson’s opinion and Judge Mayer’s dissent in Phillips.